The Pap Test Still Best Bet, but New Technologies Show Promise of Improving Screening Outcomes

This information is for reference purposes only. It was current when produced and may now be outdated. Archive material is no longer maintained, and some links may not work. Persons with disabilities having difficulty accessing this information should contact us at: https://info.ahrq.gov. Let us know the nature of the problem, the Web address of what you want, and your contact information.

The conventional Pap test is still the most effective tool available for detecting cervical cancer in adult women with average risk, according to a new evidence report produced by Duke University, an Evidence-based Practice Center (EPC), for the Agency for Health Care Policy and Research (AHCPR).

The Duke study compared three new technologies—ThinPrep®, AutoPap®, and Papnet®—to the conventional Pap test, examining their overall effectiveness and accuracy in screening performance. The study results show that the Pap test remains the most reliable test available but that the new technologies may help strengthen diagnostic accuracy in the detection of cervical cancer. The Duke researchers found that the new screening technologies for Pap testing appear to reduce significantly the likelihood that pre-malignant and malignant cells will be misdiagnosed as normal, that is, false negatives. However, little is known about the effect of these new technologies on diagnostic specificity, which is the likelihood of false positives.

"Duke University's report has provided strong evidence to guide health care professionals and public health programs in designing cervical cancer screening programs that provide the highest quality of care for their patients," said AHCPR Administrator John M. Eisenberg, M. D. "The report also clearly shows the gaps in our knowledge and areas for future research about improving the diagnosis of cervical cancer."

The study's conclusions are based on a systematic review and analysis of the best available evidence from published research. The study was conducted by the Duke University EPC, in conjunction with Health Economics Research, Inc., a Waltham, Massachusetts firm. The evidence report was peer reviewed by experts in clinical practice or research, and professional associations specializing in obstetrics, gynecology, and cytopathology. The American College of Obstetricians and Gynecologists, which recommended the literature review, served as a partner to Duke and aided in its research, and will assist in disseminating the report's findings.

Although the incidence of cervical cancer is decreasing, it is still one of the most common cancers in women. In 1998, an estimated 13,700 women developed invasive cervical cancer, and about 4,900 women died from the disease. More than 25 percent of invasive cervical cancer cases occur in women older than 65, and 40-50 percent of all women who die from cervical cancer are over the age of 65 years.

The Duke study also found:

The Pap test, while key in decreasing cervical cancer in women, is not as accurate in its diagnosis of disease as previously believed. Based on the most reliable studies, a single Pap test may miss abnormal cells in nearly half of the women who have abnormal cell growth.

Available data on the accuracy of the three technologies studied fail to describe reliable estimates for reducing false positives.

Evidence related to the accuracy of the newer technologies is incomplete.

When initial and rescreening intervals are lengthened to every 3 years or greater, the new technologies were more cost-effective than the traditional Pap test. These longer screening intervals result in lowering the costs per year of life saved.

Douglas C. McCrory, M.D., Co-Director of the Duke University EPC, said, "It is important to pick up cervical cancers early, since this condition can be treated. But it is also important to avoid false-positive screening tests, since false-positive results lead to the risk, inconvenience, and anxiety of unnecessary additional tests. It is encouraging to see the development of new technologies that may improve identification of cervical cancers. We need more complete information about the performance of new technologies in order to make informed recommendations about their use in general settings."

The Evaluation of Cervical Cytology report is part of a new series of evidence reports and technology assessments sponsored by AHCPR to provide public- and private-sector organizations with comprehensive, science-based information on common, costly conditions and health care technologies. Duke University is one of 12 AHCPR EPCs in the United States and Canada under contract to review all the relevant literature on designated topics related to prevention, diagnosis, treatment, and management of common diseases and clinical conditions. The reports will also address, where appropriate, the use of alternative or complementary therapies, and specific medical procedures or health care technologies.

Select to access an online summary of Evaluation of Cervical Cytology (AHCPR 99-E009). Print copies are available from AHCPR Publications Clearinghouse (P.O. Box 8547, Silver Spring, MD 20907; telephone within the U.S. 1-800-358-9295, and 410-381-3150 from outside the United States).

The full report will be posted on the National Library of Medicine's HSTAT database. Printed copies will be available from the AHCPR Publications Clearinghouse in early 1999.